1) Field of the Invention
The invention herein relates to a tape rule blade arrestor device that provides an improved structure for the rewinding of the tape rule blade having the capability to enhance cushioning and arresting performance to prevent the generation of enormous shearing stress by excessive rewinding speed, and thereby increase tape rule service life and utilization safety.
2) Background of the Prior Art
Referring to FIG. 1 and FIG. 2, a conventional tape rule 10 is comprised of a tape reel 13 that consists of a tensile center-wound spiral spring 131 at the interior section, a ruler blade 132 wound on the exterior section, and a hook 133 riveted to the front end of the ruler blade 132; the center section of the spiral spring 131 on the tape reel 13 is inserted over the center shaft 122 of the left case half 12; and the front end of the ruler blade 132 is positioned in the bumper block 14, which is secured inside the insertion slot 121 at the bottom section and front end of the left case half 12, with the other side of the said bumper block 14 secured inside the insertion slot 34 at the bottom section and front end of the right case half 11; and one each of the three screws 15 is inserted into the screw holes 111, 112, and 113 in the said right case half 11 and then fastened tightly into the center shaft 122 and the mounting posts 123 and 124 of the left case half 12 to complete the assembly of the tape rule 10. The conventional product is utilized by pulling out the ruler blade 10 to an appropriate length during a measurement operation and then releasing the hook 133 when measuring is finished. Since the tension of the spiral spring 131 (similar to the type utilized in most spring mechanisms) inside increases in proportion to the length unwound and, therefore, the rewinding speed is faster when the length is greater, if the said ruler blade 132 is constructed of metal, the user is susceptible to cutaneous injuries of the hand, which is an inconvenient shortcoming of the conventional product. Furthermore, if the rewinding speed is too rapid, the force of impact against the bumper block 14 is intensified, the poor cushioning performance by the structure of the bumper block 14 often leads to the dislodging of the hook 133, a serious shortcoming that preludes further utilization. However, to innovate a more practical and convenient tape rule, the inventor of the invention herein conducted exhaustive research and development based on many years of professional manufacturing experience and, furthermore, subjected the results to extensive testing and further refinement to achieve an even higher level of practical value, which finally culminated in the tape rule blade arrestor device of the invention herein.